SCOTTSDALE, Ariz. — Nolan Arenado had heard the rumors about Manny Machado, that a certain beachfront team might have been chasing the former Orioles All-Star. But his conclusion was pshaw.

“As an East Coast kid, I didn’t think he’d come all the way out to the West Coast,” Arenado said.

When the Padres finally, surprisingly, lured Machado to San Diego with a $300 million contract last month, Arenado put the pieces together. He can see baseball’s landscape like a cartographer, and he knows what is around the bend.

“Hey, man, the Padres are pretty good,” Arenado said. “They have some good players with Hoz (Eric Hosmer) and (Manuel) Margot and I’ve heard they have some really good prospects. I guess they’ll be good in the future. So it could be a really good move for them.”

Less than a week later, Arenado agreed to a $260 million deal with the Rockies and the Giants and Dodgers made brawny pitches to...